1. Field of the Invention
This invention relates to a signal compressing apparatus such as an audio signal compressing apparatus. Also, this invention relates to a signal recording apparatus such as an audio signal recording apparatus. Furthermore, this invention relates to a recording medium. In addition, this invention relates to an apparatus for an optical disc such as a CD-DA (Compact Disc Digital Audio), a CD-ROM (Compact Disc Read Only Memory), a video-CD, a DVD (Digital Video Disc), a DVD-ROM (Digital Video Disc Read Only Memory), a DVD-WO (Digital Video Disc Write Once), or a DVD-RAM (Digital Video Disc Random Access Memory).
2. Description of the Related Art
The CD (Compact Disc) standards prescribe that the sampling frequency fs should be 44.1 kHz, and the quantization bit number should be 16. There are optical recording discs on which digital signals representing audio information, digital signals representing video information, or digital signals representing both audio information and video information are recorded. Examples of such optical recording discs are a CD-DA (Compact Disc Digital Audio), a CD-ROM (Compact Disc Read Only Memory), a video-CD, and a DVD (Digital Video Disc).
Audio data conforming to the CD-DA standards can not be recorded as audio data of the CD-ROM format for the following reason. The CD-ROM format has headers containing sync information, address information, and mode information. Accordingly, a recording capacity of a CD-ROM which can be used for audio information is smaller than the audio-information recording capacity of a CD-DA.
It is a first object of this invention to provide an improved signal compressing apparatus.
It is a second object of this invention to provide an improved signal recording apparatus.
It is a third object of this invention to provide an improved recording medium.
It is a fourth object of this invention to provide an improved apparatus for an optical disc.
A first aspect of this invention provides a signal recording apparatus comprising means for quantizing an input signal into a quantization resultant signal, means for compressing the quantization-resultant signal into a compression-resultant signal; means for formatting the compression-resultant signal into a formatting-resultant signal corresponding to a predetermined format for a digital recording disc, the formatting-resultant signal including segments corresponding to user data areas prescribed in the predetermined format, the compression-resultant signal being placed in the segments of the formatting-resultant signal; means for encoding the formatting-resultant signal into an encoding-resultant signal of a CD format; and means for recording the encoding-resultant signal on a recording medium.
A second aspect of this invention is based on the first aspect thereof, and provides a signal recording apparatus wherein the input signal comprises an audio signal.
A third aspect of this invention is based on the first aspect thereof, and provides a signal recording apparatus wherein the predetermined format for the digital recording disc is equal to a predetermined format for a CD-ROM.
A fourth aspect of this invention is based on the first aspect thereof, and provides a signal recording apparatus wherein the predetermined format for the digital recording disc is equal to a predetermined format for a DVD.
A fifth aspect of this invention is based on the first aspect thereof, and provides a signal recording apparatus wherein the compressing means comprises means for subjecting the quantization-resultant signal to orthogonal transform.
A sixth aspect of this invention is based on the fifth aspect thereof, and provides a signal recording apparatus wherein the compressing means comprises means for subjecting the quantization-resultant signal to a Huffman encoding process.
A seventh aspect of this invention is based on the first aspect thereof, and provides a signal recording apparatus wherein the compressing means comprises means for dividing the quantization-resultant signal into components corresponding to divided frequency bands respectively, and means for compressing the components according to frequency-band-dependent compression characteristics depending on a predetermined auditory sensation model.
An eighth aspect of this invention provides a signal compressing apparatus comprising means for quantizing an input signal into a quantization-resultant signal; means for compressing the quantization-resultant signal into a compression-resultant signal; and means for formatting the compression-resultant signal into a formatting-resultant signal corresponding to a predetermined format for a digital recording disc, the formatting-resultant signal including segments corresponding to user data areas prescribed in the predetermined format, the compression-resultant signal being placed in the segments of the formatting-resultant signal.
A ninth aspect of this invention is based on the eighth aspect thereof, and provides a signal compressing apparatus wherein the input signal comprises an audio signal.
A tenth aspect of this invention is based on the eighth aspect thereof, and provides a signal compressing apparatus wherein the predetermined format for the digital recording disc is equal to a predetermined format for a CD-ROM.
An eleventh aspect of this invention is based on the eighth aspect thereof, and provides a signal compressing apparatus wherein the predetermined format for the digital recording disc is equal to a predetermined format for a DVD.
A twelfth aspect of this invention is based on the eighth aspect thereof, and provides a signal compressing apparatus wherein the compressing means comprises means for subjecting the quantization-resultant signal to orthogonal transform.
A thirteenth aspect of this invention is based on the twelfth aspect thereof, and provides a signal compressing apparatus wherein the compressing means comprises means for subjecting the quantization-resultant signal to a Huffman encoding process.
A fourteenth aspect of this invention is based on the eighth aspect thereof, and provides a signal compressing apparatus wherein the compressing means comprises means for dividing the quantization-resultant signal into components corresponding to divided frequency bands respectively, and means for compressing the components according to frequency-band-dependent compression characteristics depending on a predetermined auditory sensation model.
A fifteenth aspect of this invention provides a recording medium storing an encoding-resultant signal which is recorded on the recording medium by the steps of quantizing an input signal into a quantization-resultant signal; compressing the quantization-resultant signal into a compression-resultant signal; formatting the compression-resultant signal into a formatting-resultant signal corresponding to a predetermined format for a digital recording disc, the formatting-resultant signal including segments corresponding to user data areas prescribed in the predetermined format, the compression-resultant signal being placed in the segments of the formatting-resultant signal; encoding the formatting-resultant signal into an encoding-resultant signal of a CD format; and recording the encoding-resultant signal on the recording medium.
A sixteenth aspect of this invention provides an apparatus for an optical disc, comprising a CD-DA decoder; a CD-ROM decoder; a signal expansion decoder; means for reading out a signal from the optical disc; means for deciding which of a CD-DA, a CD-ROM, and a CD-ROM-audio the optical disc agrees with; means for, when the optical disc agrees with a CD-DA, selecting the CD-DA decoder from among the CD-DA decoder, the CD-ROM decoder, and the signal expansion decoder and using the CD-DA decoder to process the signal read out from the optical disc into a recovered signal; means for, when the optical disc agrees with a CD-ROM, selecting the CD-DA decoder and the CD-ROM decoder from among the CD-DA decoder, the CD-ROM decoder, and the signal expansion decoder and using the CD-DA decoder and the CD-ROM decoder to process the signal read out from the optical disc into a recovered signal; and means for, when the optical disc agrees with a CD-ROM-audio, using the CD-DA decoder the CD-ROM decoder, and the signal expansion decoder to process the signal read out from the optical disc into a recovered signal.
A seventeenth aspect of this invention provides an apparatus for an optical disc, comprising a CD-DA decoder; a CD-ROM decoder; a signal expansion decoder; an MPEG decoder; means for reading out a signal from the optical disc; means for deciding which of a CD-DA, a CD-ROM-audio, and a video-CD the optical disc agrees with; means for, when the optical disc agrees with a CD-DA, selecting the CD-DA decoder from among the CD-DA decoder, the CD-ROM decoder, the signal expansion decoder, and the MPEG decoder and using the CD-DA decoder to process the signal read out from the optical disc into a recovered signal; means for, when the optical disc agrees with a CD-ROM-audio, selecting the CD-DA decoder, the CD-ROM decoder, and the signal expansion decoder from among the CD-DA decoder, the CD-ROM decoder, the signal expansion decoder, and the MPEG decoder and using the CD-DA decoder, the CD-ROM decoder, and the signal expansion decoder to process the signal read out from the optical disc into a recovered signal; and means for, when the optical disc agrees with a video-CD, selecting the CD-DA decoder, the CD-ROM decoder, and the MPEG from among the CD-DA decoder, the CD-ROM decoder, the signal expansion decoder, and the MPEG decoder and using the CD-DA decoder, the CD-ROM decoder, and the MPEG decoder to process the signal read out from the optical disc into a recovered signal.